The present disclosure relates to an image forming apparatus provided with a cleaning device which removes a toner from an image carrier.
In an electrographic image forming apparatus, such as a printer, a facsimile machine or a multifunction peripheral, a toner remained on an image carrier is removed by a cleaning device after a toner image has been transferred to a transfer sheet. Also, in a full color image forming apparatus, an intermediate transferring belt made of resin or an intermediate transferring belt having an elastic layer is used as an image carrier.
In the case of the intermediate transferring belt made of resin, a cleaning device in which an edge of a blade made of a urethane rubber or the like presses against a surface of the intermediate transferring belt to scrape the toner is generally used because of its simple construction and inexpensiveness. On the other hand, in the case of the intermediate transferring belt having an elastic layer, there is mainly used a cleaning device in which the toner is mechanically and electrically swept from a surface of the intermediate transferring belt by a rotating brush, the swept toner is moved from the rotating brush to a collecting roller by an electrostatic force, the toner adhering to the collecting roller is scraped by a cleaning blade, and the scraped tonner is delivered to a collecting tank by a collecting screw.
In the cleaning device having the rotating brush, the collecting roller and the cleaning blade, on an upstream side from the cleaning blade in a rotating direction of the collecting roller, a sealing member is provided so as to abut against the collecting roller, preventing backflow of the scraped toner. Further, in order to prevent a leakage of the toner from both side edges of the sealing member, there may be a case in which side ends of the sealing member are supported so as to come closer to the collecting roller by side sealing members.
However, in a case where the sealing member and the side sealing members are provided, the toner or sheet powder collected on the collecting roller is dammed and accumulated by the sealing member and the side sealing members, and there may occur a failure that the accumulated tonner or the like drops. In particular, a large amount of sheet powder generated from cut faces of both side edges of the transfer sheet exists on each side end of the collecting roller. In addition, the side ends of the collecting roller are applied with a pressure from the sealing member by the side sealing members. Thus, the accumulation of the sheet powder or toner becomes remarkable at the side ends of the collecting roller.
Also, it is considered that the surface of the collecting roller is subjected to an alumite processing to form a high resistance layer on the surface and then an electrical adhesion force between the collecting roller and the toner or sheet powder is set to be higher than an abutment force between the collecting roller and the sealing member to prevent damming of the toner or the like by the sealing member and the side sealing members. However, if the adhesion force between the collecting roller and the toner is increased, it becomes difficult to scrape the toner from the collecting roller by the cleaning blade. Also, if a pressure applied from the cleaning blade to the collecting roller is increased in order to increase a toner scraping force, the cleaning blade may be shaved or a torque applied to the collecting roller or the like may be increased.